Certain monocarboxylic acid mono- and diesters of polytrimethylene ether glycol (PO3G) are expected to have properties that make them useful in a variety of fields, including as lubricants and plasticizers. Standard methods of manufacture include the polycondensation of the monomer in the presence of an acid catalyst with subsequent esterification in the same reaction vessel. However, subsequent purification of acid residues may be necessary.
Disclosed herein are methods for preparing polytrimethylene ether glycol esters starting with the glycol polymer with low levels of unreacted diol monomer.